nfsd: fix file memleak on client_opens_release

seq_release should be called to free the allocated seq_file

Cc: stable@vger.kernel.org # v5.3+
Signed-off-by: Mahmoud Adam <mngyadam@amazon.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Fixes: 78599c42 ("nfsd4: add file to display list of client's opens")
Reviewed-by: NeilBrown <neilb@suse.de>
Tested-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

fs/nfsd/nfs4state.c

@@ -2804,7 +2804,7 @@ static int client_opens_release(struct inode *inode, struct file *file)
 
 	/* XXX: alternatively, we could get/drop in seq start/stop */
 	drop_client(clp);
-	return 0;
+	return seq_release(inode, file);
 }
 
 static const struct file_operations client_states_fops = {